Global Disparities in the Characteristics and Outcomes of Leukemia Clinical Trials: A Cross-Sectional Study of the ClinicalTrials.gov Database

Most clinical trials are conducted exclusively in high-income countries (HICs), with only a small fraction involving centers from low-middle income countries (LMICs). However, studies evaluating the global distribution of clinical trials in leukemia are limited. Therefore, we sought to assess the present state of leukemia clinical trials that involve centers from LMICs and to compare those with trials conducted exclusively in HICs. We searched ClinicalTrials.gov to identify leukemia trials initiated between 2000 and 2020. In this cross-sectional study, the search strategy was developed by a medical librarian using controlled vocabulary and free-text terms. Data abstraction was independently executed by two reviewers. Trials were defined to be LMIC trials if they included centers from LMICs according to the World Bank Atlas country's income level classification for 2022-2023. Conversely, if a trial included centers from HICs only, the study was classified as a HIC trial. Of 3,345 leukemia-related clinical trials identified, only 160 (4.8%) included centers from LMICs. Compared with HIC trials, LMIC trials had lower termination rates (12.5% 27.5%; < .001) and were more likely randomized (52.5% 18.2%; < .001), larger (sample sizes >50 patients: 69.0% 33.6%; < .001), multicenter (81.9% 47.9%; < .001), and later phase (phase III: 36.2% 8.98%; < .001; phase IV: 6.25% 2.17%; < .001). There was an increase in the proportion of randomized and diseased-focused clinical trials within the trials that involved LMIC centers between 2000-2005 and 2010-2015 (57.1% 47.1% and 85.7% 52.9%; = .013 and 0.014, respectively). We found a marked underrepresentation of LMICs in leukemia clinical trials reflecting limited access to novel leukemia therapies in LMICs.